asio/impl/append.hpp

0001 //
0002 // impl/append.hpp
0003 // ~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2024 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 //
0007 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0008 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0009 //
0010
0011 #ifndef BOOST_ASIO_IMPL_APPEND_HPP
0012 #define BOOST_ASIO_IMPL_APPEND_HPP
0013
0014 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0015 # pragma once
0016 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0017
0018 #include <boost/asio/detail/config.hpp>
0019 #include <boost/asio/associator.hpp>
0020 #include <boost/asio/async_result.hpp>
0021 #include <boost/asio/detail/handler_cont_helpers.hpp>
0022 #include <boost/asio/detail/initiation_base.hpp>
0023 #include <boost/asio/detail/type_traits.hpp>
0024 #include <boost/asio/detail/utility.hpp>
0025
0026 #include <boost/asio/detail/push_options.hpp>
0027
0028 namespace boost {
0029 namespace asio {
0030 namespace detail {
0031
0032 // Class to adapt an append_t as a completion handler.
0033 template <typename Handler, typename... Values>
0034 class append_handler
0035 {
0036 public:
0037   typedef void result_type;
0038
0039   template <typename H>
0040   append_handler(H&& handler, std::tuple<Values...> values)
0041     : handler_(static_cast<H&&>(handler)),
0042       values_(static_cast<std::tuple<Values...>&&>(values))
0043   {
0044   }
0045
0046   template <typename... Args>
0047   void operator()(Args&&... args)
0048   {
0049     this->invoke(
0050         index_sequence_for<Values...>{},
0051         static_cast<Args&&>(args)...);
0052   }
0053
0054   template <std::size_t... I, typename... Args>
0055   void invoke(index_sequence<I...>, Args&&... args)
0056   {
0057     static_cast<Handler&&>(handler_)(
0058         static_cast<Args&&>(args)...,
0059         static_cast<Values&&>(std::get<I>(values_))...);
0060   }
0061
0062 //private:
0063   Handler handler_;
0064   std::tuple<Values...> values_;
0065 };
0066
0067 template <typename Handler>
0068 inline bool asio_handler_is_continuation(
0069     append_handler<Handler>* this_handler)
0070 {
0071   return boost_asio_handler_cont_helpers::is_continuation(
0072       this_handler->handler_);
0073 }
0074
0075 template <typename Signature, typename... Values>
0076 struct append_signature;
0077
0078 template <typename R, typename... Args, typename... Values>
0079 struct append_signature<R(Args...), Values...>
0080 {
0081   typedef R type(decay_t<Args>..., Values...);
0082 };
0083
0084 } // namespace detail
0085
0086 #if !defined(GENERATING_DOCUMENTATION)
0087
0088 template <typename CompletionToken, typename... Values, typename Signature>
0089 struct async_result<append_t<CompletionToken, Values...>, Signature>
0090   : async_result<CompletionToken,
0091       typename detail::append_signature<
0092         Signature, Values...>::type>
0093 {
0094   typedef typename detail::append_signature<
0095       Signature, Values...>::type signature;
0096
0097   template <typename Initiation>
0098   struct init_wrapper : detail::initiation_base<Initiation>
0099   {
0100     using detail::initiation_base<Initiation>::initiation_base;
0101
0102     template <typename Handler, typename... Args>
0103     void operator()(Handler&& handler,
0104         std::tuple<Values...> values, Args&&... args) &&
0105     {
0106       static_cast<Initiation&&>(*this)(
0107           detail::append_handler<decay_t<Handler>, Values...>(
0108             static_cast<Handler&&>(handler),
0109             static_cast<std::tuple<Values...>&&>(values)),
0110           static_cast<Args&&>(args)...);
0111     }
0112
0113     template <typename Handler, typename... Args>
0114     void operator()(Handler&& handler,
0115         std::tuple<Values...> values, Args&&... args) const &
0116     {
0117       static_cast<const Initiation&>(*this)(
0118           detail::append_handler<decay_t<Handler>, Values...>(
0119             static_cast<Handler&&>(handler),
0120             static_cast<std::tuple<Values...>&&>(values)),
0121           static_cast<Args&&>(args)...);
0122     }
0123   };
0124
0125   template <typename Initiation, typename RawCompletionToken, typename... Args>
0126   static auto initiate(Initiation&& initiation,
0127       RawCompletionToken&& token, Args&&... args)
0128     -> decltype(
0129       async_initiate<CompletionToken, signature>(
0130         declval<init_wrapper<decay_t<Initiation>>>(),
0131         token.token_,
0132         static_cast<std::tuple<Values...>&&>(token.values_),
0133         static_cast<Args&&>(args)...))
0134   {
0135     return async_initiate<CompletionToken, signature>(
0136         init_wrapper<decay_t<Initiation>>(
0137           static_cast<Initiation&&>(initiation)),
0138         token.token_,
0139         static_cast<std::tuple<Values...>&&>(token.values_),
0140         static_cast<Args&&>(args)...);
0141   }
0142 };
0143
0144 template <template <typename, typename> class Associator,
0145     typename Handler, typename... Values, typename DefaultCandidate>
0146 struct associator<Associator,
0147     detail::append_handler<Handler, Values...>, DefaultCandidate>
0148   : Associator<Handler, DefaultCandidate>
0149 {
0150   static typename Associator<Handler, DefaultCandidate>::type get(
0151       const detail::append_handler<Handler, Values...>& h) noexcept
0152   {
0153     return Associator<Handler, DefaultCandidate>::get(h.handler_);
0154   }
0155
0156   static auto get(const detail::append_handler<Handler, Values...>& h,
0157       const DefaultCandidate& c) noexcept
0158     -> decltype(Associator<Handler, DefaultCandidate>::get(h.handler_, c))
0159   {
0160     return Associator<Handler, DefaultCandidate>::get(h.handler_, c);
0161   }
0162 };
0163
0164 #endif // !defined(GENERATING_DOCUMENTATION)
0165
0166 } // namespace asio
0167 } // namespace boost
0168
0169 #include <boost/asio/detail/pop_options.hpp>
0170
0171 #endif // BOOST_ASIO_IMPL_APPEND_HPP